The present invention relates to a heat insulation structure for use in rooftops of buildings, particularly to a heat insulation structure for providing a heat insulation layer to the outside of flat roofs of concrete buildings and the like.
Recently, the exhaust of petroleum resources has become a real social problem, and thus it is now required to save energy which is consumed particularly in cooling and heating apparatus used in buildings. For this purpose various efforts have been made to improve heat insulation property of buildings by applying heat insulation treatments to them. It is advantageous to apply such heat insulation treatments to the roofs of buildings because the roofs are exposed to sunrays for a long period of time in summer and absorb heat, and because they are heated by heated air within the building and radiate heat in winter. The heat insulation treatments to the roofs of buildings, particularly concrete buildings include the so-called "outer heat insulation" treatment forming a heat insulation layer outside the roof and "inner heat insulation" treatment forming a heat insulation layer inside the roof. Particularly in concrete buildings, the "outer insulation" treatment is replacing the "inner insulation" treatment since the former provides a less heat load to roof slabs than the latter, and reduces the heat storage of the roof slabs in summer.
Generally, the "outer heat insulation" structure includes a waterproof layer disposed over the rooftop or the outer surface of the flat roof of a building, a heat insulation layer disposed over the waterproof layer, and a protective layer disposed over the heat insulation layer for protecting the latter. The heat insulation layer serves not only to provide heat insulation to the roof but also to prevent damages and heat deterioration of the water proof layer.
However, in such prior art outer heat insulation structure, the presence of the uppermost protective layer makes the maintenance of the underlying heat insulation layer and waterproof layer difficult. In most cases the protective layer is formed in place by wet construction method and thus the waterproof or heat insulation layer is liable to be damaged by trowels and the like. Furthermore, the protective layer which is formed by wet construction method is deteriorated by heat storage due to the underlying heat insulation layer and hence produces cracks which degrade the external appearance thereof. Rainwater enters through these cracks into the heat insulation layer, and hence the heat insulating material is often immersed in rainwater, so that it is deteriorated soon. It is therefore difficult to maintain the heat insulation property of the insulation layer for a long period of time.